Theoretical calculations have predicted that dark matter density distribution would be altered by a massive black hole [1]}, [2]}, [3]}, [4]}, [5]}, [6]}. The conservation of angular momentum and energy would naturally force dark matter to form a dense spike (i.e. a cusp-like density profile) [1]}, [2]}, [3]}, [5]}. Generally speaking, dark matter density around a black hole would eventually follow a simple power-law form: \(\rho _{\rm DM} \propto r^{-\gamma }\) , where \(r\)  is the radial distance from the black hole and \(\gamma \)  is the spike index. The value of \(\gamma \)  is model-dependent, which can range from \(\gamma =1.5\)  to \(\gamma =2.5\)  [2]}, [3]}, [5]}, [14]}, [15]}. Since the dark matter density profile is a singular form in \(r\) , the dark matter density near black hole would be very high (i.e. a dense spike).
